This invention relates to a waveform to pulse conversion technique and more particularly to techniques for converting arbitrary analog waveforms to sequences of pulses.
Pulse generators are well known, for example, for DC controllers and other applications. However, the typical pulse generator is an adaptation of a conventional oscillator or monostable multivibrator, which can produce undesired or spurious transients when the pulse triggering is terminated. Such transients could be confused with trailing pulses, so that the counting of pulses is an inaccurate representation of the intended pulse count.
A typical pulse generator is responsive to a trigger related to a threshold level; that is, pulses are generated when a level input is applied that exceeds a predetermined threshold that has established a trigger point. The duration of the input above the threshold typically corresponds to the duration of the pulse train or oscillation period.
A classic van der Pol (vdP) oscillator is a simple nonlinear oscillator circuit and is a useful starting point for use as a pulse generator. However, the classic vdP oscillator is not readily controlled.
U.S. application Ser. No. 09/429,527 discloses circuitry that controls oscillations. However, the disclosed circuitry is frequency dependent. In some situations, this is an undesirable property, especially when dealing with a signal that has a broadband frequency spectrum. The power transfer to the circuitry for certain frequency range is better than others. Circuitry is needed which is simple and yet which addresses needs in specialized applications. There is a need for an improved controlled relaxation oscillator.
According to the invention, a circuit is provided for generating output pulses or oscillations in response to input analog waveforms. The circuit has a variable operating point and a transfer function characterized by an unstable operating region bounded by a first stable operating region and a second stable operating region. The circuit is further characterized by having a resistive input impedance.
The invention will be better understood by reference to the following detailed description in connection with the accompanying drawings.